The Nineteenth Byte

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00:23

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How Shuffled is This Sequence? Given a sequence \$S\$ with length \$n\$ of exactly one each of whole numbers from \$1\$ to \$n\$, your task is to return a number \$\sigma\$ indicating how shuffled it is. The shuffledness algorithm Total a 'shuffledness' value for each element \$\sigma_i\$ in s...

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01:04

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A: Sandbox for Proposed Challenges

Is this board Latin-style? code-golf decision-problem grid sudoku Inspired by Flow Fit: Sudoku, a brand-new mobile puzzle game (as of Nov 2019). Background A Latin square is a square grid of side length \$ n \$ filled with \$ n \$ different symbols, where each row and column contains each symb...

New Main Posts

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Q: Best movement to archive highest score

Giving a set of 33 objects 11 red, 11 yellow and 11 blue, with 5 special towers in which can only contain one color and when a color is placed, all the same color object scores are increased by one point. Ex.( redValue =1; if one red obj placed on special tower, redValue = 2). The cubes can also ...

caird coinheringaahing

02:47

@RedwolfPrograms No, that's not the point. The point is to create a challenge which is theoretically perfectly doable, but completing it is all about finding the obscure features/languages which make it less of an impossible task

Redwolf Programs

@cairdcoinheringaahing I know, I was joking (-:

caird coinheringaahing

CMC: code-trolling Make a program that proves P=NP

"Most creative" wins

John Dvorak

03:09

vtc: no objective criterion

A̲̲

03:52

@cairdcoinheringaahing It's very easy. Works in most languages: P=NP

@RedwolfPrograms I envy people who like their own languages.

caird coinheringaahing

@A̲̲ From someone whose made (arguably) way too many: the trick is to base them around something you find interesting

Bubbler

@cairdcoinheringaahing Coq: Definition P := 1. Definition NP := 1. Theorem P_is_NP : P = NP. Proof. auto. Qed.

caird coinheringaahing

Whenever I learn something new CS/math related, I create a language with that as the core principle

Unrelated String

04:17

I've been trying to write a language in the same way I've been trying to write a challenge: waiting for inspiration that won't actually come

New Main Posts

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Q: How close are we, really?

Each natural number \$n\$ has 10 faces: its decimal representations in bases \$1\$ through to \$10\$. For example, the 10 faces of \$12\$ are \$[111111111111, 1100, 110, 30, 22, 20, 15, 14, 13, 12]\$, and the 10 faces of \$4\$ are \$[1111, 100, 11, 10, 4, 4, 4, 4, 4, 4]\$ We can then say that tw...

code-golf math restricted-source base-conversion

A̲̲

@NewMainPosts The best inspiration is to modify other peoples' challenges.

caird coinheringaahing

@A̲̲ Wrong reply? :P

Redwolf Programs

05:42

@UnrelatedString I just try to find some sort of challenge in the language design, like "it only has three characters" or "it's based on a 3d cube of instructions"

The feeling of waiting for inspiration for a challenge idea though, that's the worst

Bubbler

05:59

For writing challenges, I go through random Wikipedia articles or Google search with pseudorandom keywords until I find something interesting

The topic is mostly math-related in my case

Newly Featured Questions

06:55

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Q: Rearranging the sequence

Introduction Let's observe the following sequence (non-negative integers): 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, ... For example, let's take the first three numbers. These are 0, 1, 2. The numbers used in this sequence can be ordered in six different ways: 012 120 021 201 102...

code-golf number sequence combinatorics permutations

New Sandboxed Posts

08:16

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A: Sandbox for Proposed Challenges

disclaimer: this is extremely experimental and should probably not be taken seriously. Feel free to point out how bad this idea is. This is obviously not completely specified yet. Win the competition king-of-the-hill Write a program that, given two programs, picks the winner. The choice m...

Bubbler

08:26

@NewSandboxedPosts Probably the most chaotic king-of-the-hill ever, if it goes well.

Neil

10:36

@NewMainPosts Without source restriction, this is 25 bytes in Charcoal: ＦＡ⊞υＥχ⎇κ⍘ι⊕κ×1ιＩΣＥ⊟υ№§υ⁰ι

A̲̲

12:23

@NewSandboxedPosts The easiest koth that I've ever seen (until OP takes counter-measures).

flawr

12:45

@A̲̲ I wouldn't say it is easy.

A̲̲

*simple

Redwolf Programs

13:54

Reminds me of mine a little, an odd, fun idea that probably wouldn't work in practice

Adám

14:11

@RedwolfPrograms A perpetuum mobile?

Redwolf Programs

My sandboxed KoTH, a JS free for all

Adám

"an odd, fun idea that probably wouldn't work in practice":

Perpetual motion

Perpetual motion is motion of bodies that continues indefinitely. A perpetual motion machine is a hypothetical machine that can do work indefinitely without an energy source. This kind of machine is impossible, as it would violate the first or second law of thermodynamics.These laws of thermodynamics apply regardless of the size of the system. For example, the motions and rotations of celestial bodies such as planets may appear perpetual, but are actually subject to many processes that slowly dissipate their kinetic energy, such as solar wind, interstellar medium resistance, gravitational radiation...

Redwolf Programs

Yeah, fair enough comparison

flawr

@Adám would probably exacerbate our climate crysis:)

Redwolf Programs

@Adám I don't know, this guy says he made one!

We just have to pretend monopoles exist!

John Dvorak

14:21

Wasn't that proven impossible by virtue of magnetic field being equivalent to orthogonal electric field via Lorentz boost?

Redwolf Programs

I love when people say they've created perpetual motion machines that will create "free energy"

Taking energy from the machine would slow it down, no matter how "perpetual"

Adám

@flawr Yeah, a run-away PM machine would be very bad.

flawr

@RedwolfPrograms But a perpetual motion machine must produce at least as much energy that it is consuming to keep running, doesn't it?

Redwolf Programs

My idea of perpetual motion is a completely frictionless spinning disk. It doesn't lose any energy, or create any

Adám

> uses a mono polar magnet

Ugh.

flawr

14:23

@Adám You just have to cut these spins in half.

Redwolf Programs

I'd like to know what scientists manage to disprove the laws of thermodynamics, but can only afford a skateboard wheel

Adám

Magnetic monopoles work best if painted monochromatic magenta.

4

Redwolf Programs

XD

@Adám I doubt it, since the energy would probably be generated purely as mechanical energy to keep it spinning, so it would just get faster and faster until it either broke or jumped into the future

Adám

@RedwolfPrograms Assuming the mechanical energy isn't rotational in an absolute vacuum chamber (which is of course impossible, but whatever), there'll be friction and so the atmosphere will be heated.

Actually, even a flywheel magnetically suspended in vacuum would affect the Earth's rotational energy.

Redwolf Programs

Ah, true. I guess we'd just need a climate activist with a sledgehammer.

Adám

14:31

True PMs don't require generation of energy, as they are stable. Why did they need to give it such a totally sci-fi sounding name…

Time crystal

A time crystal or space-time crystal is a structure that repeats in time, as well as in space. Normal three-dimensional crystals have a repeating pattern in space, but remain unchanged as time passes. Time crystals repeat themselves in time as well, leading the crystal to change from moment to moment. If a discrete time translation symmetry is broken (which may be realized in open driven systems) than the system is referred to as a discrete time crystal. A discrete time crystal never reaches thermal equilibrium, as it is a type of non-equilibrium matter, a form of matter proposed in 2012, and first...

Redwolf Programs

Huh, cool

But it'll never beat skateboard wheel with mono polar

Adám

@RedwolfPrograms ~~monopole~~ mono polar

New Sandboxed Posts

14:46

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A: Sandbox for Proposed Challenges

Pascal's Combination and Permutation Investigation Pascal is rather annoyed. He's claimed ownership of the triangle of cool numbers, but can't see what possible uses it has other than simply being "slightly interesting for a bit". He's turned that job over to you, and you know just the thing tha...

AdmBorkBork

15:41

@Adám Reminds me of the Time Cube.

Veskah

Classic time cube

flawr

16:12

@Adám that is actually used for fly-wheel energy storage

Jonah

16:27

Hey all, a question inspired by an actual problem. It may make a good CG post, but I want to make sure I'm not missing an obvious solution. The problem is: you have a bunch of small rectangles that you want to scatter "randomly" within a larger rectangle. Think: a bunch of playing cards places in random positions on a table. Constraints: No rotation (the cards edges will remain parallel to the table edges) and no overlap (cards won't overlap each other).

Is there a simply algorithm to achieve this? My initial idea is to scatter dots uniformly (1 dot per card representing the upper left coord for a card) and then do a second pass to deal with removing overlaps.

feersum

So what is your desired distribution?

Can they be rotated 90 degrees?

Jonah

feersum: Uniform or something close-ish to that. It's not too important as long as it "feels" random enough.

"Can they be rotated 90 degrees?" -- No.

Potato44

Are all small rectangles the same size?

Jonah

Potato44: Not necessarily.

Potato44

The naive way of just picking positions for each each card randomly and trying again if it overlaps can fail in some situations. Example: the large rectangle is 4 cards wide and 1 card tall, we want to place 3 cards. The first card(s top-left corner) gets placed at (2/3,0) the second card at (7/3,0). but now we don;t have a large enough space to place the 3rd card.

feersum

16:48

In the cramped table limit, the problem of just determining whether the cards can fit at all is NP-hard.

Apparently it's called the "rectangle fit problem".

Jonah

Interesting. In the real-world case I'm solving the containing rectangle will be "big enough", so the "try the whole thing again" algorithm Potato suggested is probably practical.

feersum

In the large table limit you can just do rejection sampling (completely start over if you get an overlap) and get a totally uniform distribution.

Jonah

18:03

Yeah, I think that might be enough for me. Thanks guys.

Nathan Merrill

@feersum I think this only applies to rectangles of different sizes

DJMcMayhem

18:51

Sometimes I wonder why I'm allowed to be a programmer.

I just did this: Try it online! and I spent 40 minutes trying to find out why f() wasn't being called.

What does that even do? Why is that allowed?

ngn

19:17

@DJMcMayhem void is special kind of a unary operator, it prevents evaluation of its argument

Christian Sievers

@DJMcMayhem You can add or change two characters to make it work :-)

DJMcMayhem

I could make it work with one character added

@ngn Try it online! works too

Although that's easier to understand I suppose. Declares an integer f and calls it's constructor with an empty expression

ngn

oh... in this case i guess the compiler took it as a function declaration, not a unary operator, i was wrong

so, your main re-declares f without doing anything

DJMcMayhem

Ooooh. Kinda like when you use class a; for forward declaration

I've made stupid errors similar to that too many times to count. Like doSomething(callback=f()) rather than doSomething(callback=f)

And JS's incredibly lax type system means that won't error until the last possible minute

Christian Sievers

@DJMcMayhem You can do stuff like Try it online!

DJMcMayhem

19:25

@ChristianSievers Even better: Try it online!

Christian Sievers

@DJMcMayhem But that doesn't try to justify your local declaration

ngn

today i discovered an elegant way to make c return the result from the last expr in a function: #define _(a...) {R({a;});}

3

and then instead of int f(int x,int y){return x+y;} you write int f(int x,int y)_(x+y)

there could be more exprs/statements before x+y, separated with ;

Redwolf Programs

19:51

@DJMcMayhem I pretty much did the exact same thing once...I tried to set the callback of a function to log, and instead set it to log() (which evaluated to nothing), so I sat there for 20 minutes wondering why it hadn't finished a POST request yet...

ngn

@ngn i forgot to say, R is defined as return

DJMcMayhem

@RedwolfPrograms Yeah, type safety is nice

flawr

@DJMcMayhem haa... haaaa.... haaaaaaaaaa. .........haskell

New Main Posts

22:33

-1

Q: Rayo's Function

I am interested in large numbers. REALLY large numbers. I just found out about busy beaver numbers (they are pretty interesting), and there is another large class of numbers: Rayo's numbers. I am making this challenge for all interested code-golfers: calculate the first values of Rayo's function....

number-theory

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